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=LAB PREPARATION=
{| width="40%" align="right" cellpadding="10"
|style="padding-left:20px;" |User Management
[httphttps://unixhelpwww.edsystutorials.ac.ukcom/docs/CGIlinux/man/8-cgi?useradd+8 / useradd]<br>[httphttps://unixhelpwww.edsystutorials.ac.ukcom/docs/CGIlinux/man/8-cgi?userdel+8 / userdel]<br>[httphttps://unixhelpwww.edsystutorials.ac.ukcom/docs/CGIlinux/man/8-cgi?usermod+8 / usermod]<br>[httphttps://unixhelpwww.edsystutorials.ac.ukcom/docs/CGIlinux/man/8-cgi?groupadd+8 / groupadd]<br>[httphttps://unixhelpwww.edsystutorials.ac.ukcom/docs/CGIlinux/man/8-cgi?groupdel+8 / groupdel]<br>
[http://www.agr.unideb.hu/~agocs/informatics/11_e_unix/unixhelp/unixhelp.ed.ac.uk/CGI/man-cgied74.html?chage chage]<br><br>
Managing Services<br>
[http://www.dsm.fordham.edu/cgi-bin/man-cgi.pl?topic=systemctl systemctl]<br>
|style="padding-left:20px;" |Miscellaneous
[http://zenit.senecac.on.ca/wiki/index.php/Init_vs_systemd init vs systemd]
|}
= INVESTIGATION 1: User/Group Management =
# Be sure to record your observations in your lab notes.
#Issue the man pages for the '''useradd''' command. Explain the purpose of using the '''-e''' option for the ''useradd'' command.
#Issue the following command: <b><code><span style="color:#3366CC;font-size:1.2em;">chage -E 20182019-0512-31 ops235_1</span></code></b>
#Issue the following command: <b><code><span style="color:#3366CC;font-size:1.2em;">usermod -c "New Name" ops235_2</span></code></b>.
#View ops235_2's account information in the '''/etc/passwd''' file. What do you notice is different?
|}
=== Part 3: Managing Groups ===
In this section, we will learn how to create, remove and modify groups in our Linux VM. You learned in ULI101 how to change permissions with the '''chmod''' command, but you didn't have admin privileges to '''create groups''' to allow directory and regular file sharing. Since you now have admin privileges with your VM, you can now create groups, and add users to this group to allow file-sharing among users.
# Use the commands you used in Lab2 to '''stop''' and '''disable''' the iptables service.
# Issue a command to verify you '''disabled''' and '''stopped''' the iptables service.<br><br>'''Note:''' There is a major difference between stopping a service and disabling a service: If a service is stopped but enabled, the service will start upon reboot. Therefore to prevent it being started upon boot-up, the service will need to be disabled as well!<br><br>
# Issue the commands to '''start''' and '''enable''' the iptables service, and '''verify''' that it is <u>started</u> and <u>enabled</u>.<br><br>'''Note: ''' If you performed the commands correctly, the iptables service should be running, and will automatically run upon your Linux machine start-up.
===Part 2: How do we Manage Runlevels?===
Running Linux servers in graphical mode will can make your system most likely the server vulnerable to penetration (i.e. a potential break-in to be penetratedthe server from unauthorized intruders). The X-windows framework can be vulnerable to attacks when these servers are connected to the Internet. This is why when you install '''server versions ''' of Linux, they work in text-based mode only. Desktop versions of Linux are then installed on workstations (working in graphical mode) that connect to the '''Linux server ''' (for security reasonssince those servers are closest to the router and the Internet).
The Linux sysadmin can also change the run-level (or state) of a graphical Linux server to run in text-based mode and run the graphical mode by issuing a command when graphic mode is required. The run-level term is now deprecated in Fedora, and will likely be deprecated in RHEL/CentOS at some point as well, but for now this is what the industry is using.
# Remain in your '''centos1''' VM for this section.
# Issue the following Linux command: <b><code><span style="color:#3366CC;font-size:1.2em;">runlevel</span></code></b><br><br>'''Note:''' You should see two separate characters (like N 5). The number on the right is the current run-level 5 (which is graphical mode). The number or character on the left if the previous run level (which is N which means there was no previous run level since it was a "new" install).<br><br>
# You can use the '''init''' command to change the current run-level. See a list of runlevels [https://www.centos.org/docs/5/html/5.2/Installation_Guide/s2-init-boot-shutdown-rl.html here].
# Issue the '''init''' command to change the current run-level in '''centos1''' to '''3''' by issuing the following command:<br><b><code><span style="color:#3366CC;font-size:1.2em;">init 3</span></code></b>
# What did you notice?
# Issue the following Linux command: <b><code><span style="color:#3366CC;font-size:1.2em;">startx</span></code></b><br>What happens? Why would you want to make a graphical Linux system run in text-based mode?
# Log-off your graphical system. You should return to your CLI shell prompt; therefore and change to root user. You should notice at this point that the command '''startx''' did not reset your run-level.
# Reissue the '''init''' command to change the current run-level back to '''5'''<br>Did it work?
# Issue the runlevel command to verify that the run-level is set to '''5''' (i.e. Graphical). You should notice a '''3 followed by a 5'''. That is to indicate that the '''current''' run-level is 5, but <u>previously</u>, it was set to 3.
'''Answer INVESTIGATION 2 observations / questions in your lab log book.'''
= INVESTIGATION 3: CREATING LINUX COMMANDS VIA SHELL SCRIPTS=
#Open a shell terminal, and login as root.
#Change to the '''/root/bin''' directory.
#Download, study, and run the following shell script. Issue the command:<br><b><code><span style=" pointer-events:none;cursor:default;color:#3366CC;font-size:1.2em;">wget https://scs.senecacict.onsenecacollege.ca/~murray.saulops235/lab4/user-create.bash</span></code></b>
#Try to understand what these Bash Shell scripts do, and then run the script as root to create just one user called '''test'''. After running the shell script, view the contents of the '''/home''' directory to confirm.
<ol><li value="6">Open a Bash shell terminal and login as root.</li><li>Change to the '''/root/bin''' directory.</li><li>Use the wget command to download the input file called user-data.txt by issuing the command:<br><b><code><span style="color:#3366CC;font-size:1.2em;">wget https://scsict.senecac.onsenecacollege.ca/~murray.saulops235/lab4/user-data.txt</span></code></b></li><li>View the contents on the user-data.txt file to confirm there are 3 fields (username, fullname, and e-mail address)which are separated by the colon (:) symbol.</li><li>Use a text editor (such as <b><code><span style="color:#3366CC;font-size:1.2em;">vi</span></code></b> or <b><code><span style="color:#3366CC;font-size:1.2em;">nano</span></code></b>) to create a Bash Shell script called: <b><code><span style="color:#3366CC;font-size:1.2em;">createUsers.bash</span></code></b> in the /root's home /bin directory.</li><li>Enter the following text content into your text-editing session:</li></ol>
<code style="color:#3366CC;font-family:courier;font-size:.9em;margin-left:20px;font-weight:bold;">
<br>
# Switch to your '''c7host''' VM.
# Open a shell terminal, '''su -''' into root, and change to the '''/root/bin''' directory.
# Issue the Linux command: <b><code><span style="color:#3366CC;font-size:1.2em;">wget httphttps://matrixict.senecac.onsenecacollege.ca/~murray.saulops235/ops235lab4/lab4-check.bash</span></code></b>
# Give the '''lab4-check.bash''' file execute permissions (for the file owner).
# Run the shell script and if any warnings, make fixes and re-run shell script until you receive "congratulations" message.
#Arrange proof of the following on the screen:<br><span style="color:green;font-size:1.5em;">✓</span> '''centos1''' VM:<blockquote><ul><li>Demonstrate that this VM 's current run-level is set to '''5'''.</ul></blockquote><span style="color:green;font-size:1.5em;">✓</span>'''c7host''' machine<blockquote><ul><li>Run the '''lab4-check.bash''' script in front of your instructor (must have all <b><code><span style="color:#66cc00;border:thin solid black;font-size:1.2em;"> OK </span></code></b> messages)</li></ul></blockquote><span style="color:green;font-size:1.5em;">✓</span> '''Lab4''' log-book filled out.
= Practice For Quizzes, Tests, Midterm & Final Exam =
[[Category:OPS235]]
[[Category:OPS235 Labs]]
[[Category:CentOS 7]]
[[Category:SSD2]]
